GasGasGas - Anaesthetic Science for Anaesthesia! Thiopentone: Barbiturate Anaesthesia, does it still have a place?
Oct 11, 2024
The podcast dives into the fascinating world of thiopentone, highlighting its rapid onset and classic role in induction anesthesia. Listeners learn about its formulation, the crucial pharmacokinetics, and practical uses in medical settings. Warnings about rare risks like anaphylaxis and tissue necrosis are discussed, alongside insights on zero-order kinetics and protein binding intricacies. Anecdotes from history add a compelling layer, reflecting on thiopentone's past applications and relevance in today's medical practice.
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Exceptionally Fast Induction
- Thiopentone produces hypnosis in one arm‑brain circulation time and is faster than propofol, ketamine and etomidate for induction.
- Its classic use is in rapid sequence induction paired with suxamethonium but causes a brisk laryngoscopy pressor response if opioids are sparse.
Alkaline Syringe, Lipid‑Active In Blood
- Thiopentone is a barbiturate presented alkaline in syringe and undergoes tautomerism to become lipid soluble after injection.
- It acts at GABA receptors and is useful for induction, refractory seizures, and lowering intracranial pressure.
Saturable Metabolism Gives Long Tail
- Thiopentone is hepatically metabolised with partly saturable (zero‑order) kinetics and forms active pentobarbitone.
- Redistribution half‑life is ~8 minutes but clearance can be hours, so infusions give prolonged context‑sensitive effects.